The causes of brain tumours have been hard to discern in most cases. But Umeå researchers have previously identified an inherited predisposition for brain tumours, and now, in an international collaboration, they have also discovered a genetic variation that increases the risk of a certain type of brain tumour, called meningiomas. Approximately 1 400 people are affected annually by tumours of the brain in Sweden and twenty per cent of those are afflicted with meningioma. The tumour itself is usually benign, but it can cause severe symptoms owing to of its location and because it is sometimes malignant. It arises from the meninges, and it is more common among women.